The present invention relates to an apparatus for swaging an object, and particularly relates to an apparatus for swaging an end of a tubular member, such as a length of casing or drillpipe used in the oil and gas industry.
Conventionally, casing tubulars have a standard pin type connector at each end, and one end of a casing tubular is connected to an end of another casing tubular by means of a casing joint, commonly known as a coupler, and which comprises a short length of tube having a standard box type connector at each end. Alternatively, tubulars, such as drill pipe in particular, have a standard pin type connection at one end and a standard box type connection at the other end.
It is important that a made up tubular string, such as a casing, lining or drill string has a substantially linear throughbore at the joints between the respective tubulars, and couplers if present.
The pin and/or box connections are conventionally made up on a tubular by first swaging respectively inwardly or outwardly the outer diameter of the ends of the pipe by a suitable amount so that pins can be formed. This swaging of the outer diameter of the pipe necessarily respectively reduces or increases the internal diameter of the pipe end.
After the end of the pipe has been swaged, the internal or external diameter of the end of the pipe is then machined. The swaging process ensures that there is material around the entire circumference of the internal or external diameter of the pipe that can be machined away, thereby achieving concentricity of the internal or external diameter of the pipe end. Additionally, this ensures that there are no thick or thin sections of wall thickness on the pipe end, thereby ensuring a constant wall thickness to the pipe end.
Thereafter, the screw thread of the pipe end can be formed on its outer or inner circumference.
A conventional machine for swaging an end of a pipe comprises a swaging head having a single swaging formation thereon for swaging a particular diameter of pipe. The pipe to be swaged is held between a semi-circular lower clamp and two upper quarter circular segments, where the two upper segments are hinged to the lower semi-circular clamp to permit the pipe to be inserted into the clamp. The clamp is provided with plurality of teeth, in a saw tooth arrangement, to grip the pipe. However, with the saw tooth arrangement, the teeth tend to bite into and damage the outer wall of the pipe. Furthermore, where the pipe has slight variations in the outer circumference of its wall, the teeth will tend to grip certain parts of the outer diameter more forcefully than other parts, since the clamping device is substantially immoveable once it has been closed.
According to a first aspect of the present invention, there is provided an apparatus for swaging an end of a tubular, the apparatus comprising a swaging head for providing the swage to the end of the tubular, wherein the swaging head has two or more swaging formations provided thereon to permit swaging of differing diameters of tubular ends.
The swaging formation may be provided on an internal bore of the swaging head, such that the internal bore of the swaging head engages the outer diameter of the tubular end to provide the swage thereto.
Each swaging formation may comprise a first diameter of the swaging head, a second diameter being smaller than the first diameter, a third diameter being smaller than the second diameter, and a fourth diameter being smaller than the third diameter. Preferably, the internal bore of the swaging head tapers substantially linearly inwardly, with respect to the longitudinal axis of the swaging head, from the first diameter to the second diameter, and from the second diameter to the third diameter. Typically, the angle of the taper from the first to the second diameter is greater than the angle of the taper from the second to third diameter. Typically, the surface of the internal bore of the swaging head provided by the taper from the first to the second diameter is a guiding surface, and the surface provided by the taper from the second to third diameter is a swaging surface.
The surface of the internal bore of the swaging head from the second/third diameter co the third/fourth diameter may be arranged to be substantially perpendicular to the longitudinal axis of the swaging head, and is preferably arranged to provide a shoulder or a stop surface against which the tubular end arrests.
Preferably, the swaging head is arranged with at least first and second swaging formations, whereby the fourth diameter of the first swaging formation is greater than the first diameter of the second swaging formation. Typically, the first diameter of the first swaging formation is the closest diameter of all of the diameters of all of the swaging formations to the tubular end, in use.
Alternatively, the swaging, formation may be provided on an external diameter of the swaging head, such that the external diameter of the swaging head engages the inner diameter of the tubular end to provide the swage thereto.
Each swaging formation may comprise a first diameter of the swaging head, a second diameter being greater than the first diameter, a third diameter being greater than the second diameter, and a fourth diameter being greater than the third diameter. Preferably, the external diameter of the swaging head tapers substantially linearly outwardly, with respect to the longitudinal axis of the swaging head, from the first diameter to the second diameter, and from the second diameter to the third diameter. Typically, the angle of the taper from the first to the second diameter is greater than the angle of the taper from the second to third diameter. Typically, the surface of the external diameter of the swaging head provided by the taper from the first to the second diameter is a guiding surface, and the surface provided by the taper from the second to third diameter is a swaging surface.
The surface of the external diameter of the swaging head from the second/third diameter to the third/fourth diameter may be arranged to be substantially a perpendicular to the longitudinal axis of the swaging head, and is preferably arranged to provide a shoulder or a stop surface against which the tubular end arrests.
Preferably, the swaging head is arranged with at least first and second swaging formations, whereby the fourth diameter of the first swaging formation is smaller than the first diameter of the second swaging formation. Typically, the first diameter of the first swaging formation is the closest diameter of all of the diameters of all of the swaging formations to the tubular end, in use.
Two or more swaging formations may be provided.
According to a second aspect of the present invention, there is provided an apparatus for swaging an end of a tubular, the apparatus comprising a swaging head for swaging the end of the tubular, and a stop plate for abutment against the other end of the tubular, the swaging head and the stop plate being movably coupled to one another.
Movement of the swaging head and the stop plate toward one another typically facilitates swaging of the said one end of the tubular.
Typically, the swaging head is moveable toward the stop plate by means of a piston, and preferably, the swaging head and the stop plate are movably coupled to one another by a frame. Typically, the frame is adjustable such that distance between the stop plate and the swaging head can be further varied by adjustment of the frame.
Typically, the frame comprising at least one member coupled to both of the swaging head and the stop plate, and preferably the coupling between the member and at least one of the stop plate and swaging head can be adjusted in order to vary the length of the member between the swaging head and the stop plate. Preferably, the coupling between the member and the stop plate is in the form of a screw thread engagement.
Preferably, the stop plate comprises a bore and a device for obturating the bore, such that when the device obturates the bore, the device abuts the said other end of the tubular. Typically, the device is removable from the stop plate such that a tubular to be swaged may be passed through the bore. This provides the invention with the advantage that the device can be inserted into or over the bore so that short lengths of tubular can be swaged, and the device can be removed from the stop plate so that longer lengths of tubular can be swaged.
According to a third aspect of the present invention provides an apparatus for swaging an end of a tubular, the apparatus comprising a swaging head for swaging the end of the tubular, and a clamping device for clamping the tubular, the clamping device being split into at least three part-circular clamping segments which clamp substantially around the outer circumference of the tubular to permit it to be swaged.
Preferably, there are at least four part-circular clamping segments which clamp substantially around the outer circumference of the tubular to permit it to be swaged.
Preferably, there are two clamping devices provided, typically a forward clamping device which is arranged to be closest to the swaging head, and a rear clamping device which is arranged to be furthest from the swaging head.
Typically, the clamping segments are housed within a clamping ring, and may be mounted on the clamping ring in an arrangement such that the segments can move, preferably only to a relatively small degree, with respect to the ring.
Preferably, the clamping ring is split into at least two part circular members, where the members may be hinged together, such that the ring may be opened to permit a tubular to be inserted into the ring, and closed to clamp the segments around the tubular.
Typically, a range of segments can be housed within the ring, where the range of segments may be of varying radial thickness, to permit a range of differing diameter tubulars to be clamped.
According to a fourth aspect, the present invention provides an apparatus for swaging a tubular, the apparatus comprising a swaging head for swaging the end of the tubular, and a clamping device for clamping the tubular, the clamping device having a plurality of teeth for gripping the outer surface of the tubular, and a plurality of grooves formed between the teeth, wherein the gripping surface of each tooth is substantially parallel co the longitudinal axis of the tubular to be gripped.
This provides the invention with the advantage that the teeth do not bite into the outer surface of the tubular, thus avoiding damaging the tubular.
The grooves may be formed with two side walls which are substantially perpendicular to the longitudinal axis of the tubular to be gripped, and may be formed with a lowermost surface which is substantially parallel to the longitudinal axis of the tubular to be gripped.
An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: